Clarity problem: needlessly complex phrase. The modifier string ("the right booster's aft field joint's primary O-ring") is too long for the reader to comprehend in one pass.

Possible solution: Break up the string ("the primary O-ring on the aft field joint of the right booster..."). For further discussion, see pages 85-86.

Precision problem: imprecise level of detail. Given the use of "approximately," the number of microprocessors is overspecified.

Possible solutions: Either make the number less specific ("about two thousand microprocessors") or cut the modifier ("Within the master control there are four computers and 1943 microprocessors"). For further discussion, see pages 80-81.

Clarity problem: ambiguity arising from syntax. Was the schedule discussed for four years or was there a four-year schedule?

Possible solution: Move the prepositional phrase ("The proposed four-year schedule is discussed below"). For further discussion, see pages 92-93.

Clarity problem: ambiguity arising from punctuation problem. The reader trips thinking that one beam has passed the output of the opposite beam.

Solution: Place a comma after word "passes." For further discussion, see pages 94-96.

Clarity problem: needlessly complex sentence. The sentence contains too many ideas.

Possible solution: Break up the sentence into two or three sentences. First revision: "The goal of this research on silver/polymer reflectors is to develop and test at least one durable material for use in a low-cost, lightweight concentrator. This reflector material must be resistant to ultraviolet radiation and pollution attack. It must also have a useful life of 15 years and a specular reflectance of greater than 90 percent, which is comparable to that for silver/glass mirrors." For further discussion, see pages 86-90.

Clarity problem: ambiguity arising from syntax. The placement of the word "only" causes an ambiguity. Was the lunar module designed for only two purposes (to hold two astronauts and to exist for forty-five hours)? Or was the lunar module designed to hold only two astronauts? )? Or was the lunar module designed to exist for only forty-five hours?

Possible solution: Rethink the position and use of the word "only." First revision: "The Lunar Module was designed to accommodate at most two astronauts and to operate at most for forty-five hours." For further discussion, see pages 92-93.

Precision problem: imprecise word choice. The word "credited" has a positive connation, which is out of place in the sentence.

Possible solution: Replace the word "credited" with the word "blamed." Revision: "A physician named Irving Selikoff blamed asbestos with causing two types of lung cancer: asbestosis and mesothelioma." For further discussion, see pages 77-78.

Clarity problem: ambiguity arising from pronoun. What does the word "this" refer to? Only the writer knows for sure. Note that this problem could be considered a discontinuity (see pages 137-138).

Possible solution: Add specific details that help make the transition from the problems encountered to the decision about the length of time that researchers can work in the biosphere. For further discussion, see pages 92-93.

Clarity problem: needlessly complex sentence. The sentence contains too many ideas (reflected by the number of parenthetical commas).

Possible solution: Break up the sentence into two or three sentences. First revision: "Modern mining companies, which are enormous and high-tech, are both continuing operations at old gold mines and opening new ones. An example of an old gold mine is the Homestake Mine in Lead, South Dakota. This mine has operated continuously since 1877 and is continuing to increase its operations [Hinds and Trautman, 1983]. An example of a new gold mine is the proposed New World Mine, which is to be about 2.5 miles from the border of Yellowstone National Park, near Cooke City, Montana. The construction of this mine has been postponed." For further discussion, see pages 86-90.

Clarity problem: ambiguity arising from punctuation problem. The reader trips thinking that the airplane has waited too long to take off de-icing fluid.

Possible solution: Place a comma after word "off." For further discussion, see pages 94-96.